Metalworking machine



Nov. 18, 1947.V H, L, KNAPP METAL WORKING MACHINE Filed Feb. '16, 1945 5 sheets-sheet i NOV. 18, H' L KNAPP METAL WORKING MACHINE 5 Sheets-Sheet 2 Filed Feb. 16, 1945 Nov. 18, 1947. H. L. KNAPP METAL WORKING MACHINEv Filed Feb. 16, 1945 3 Sheets-Sheet 5 INVENTOR.

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MYSKDVQ Patented Nov. 18, 1947 METALWORKING MACHINE Harry L. Knapp, Detroit, Mich.

Application February 16, 1945, Serial No. 578,299

9 Claims.

This invention relates to metal working machines of the general class in which it is desired to carry out such machining operations as grinding, milling, reaming, shaping, etc. In the illustrated embodiment of the invention the machine is adapted to perform internal grinding operations on a tubular workpiece, this being accomplished by means of a grinding Wheel carried by a rotary grinding spindle which is reciprocated toward and from the workpiece.

An object of the invention is to provide a metal working machine having improved mechanism for reciprocating the tool spindle.

A further object of the invention is to provide improved means for shifting the tool toward and from the work while at the same time imparting to the tool a variable rate of travel during each cycle of operation.

More specically it is an object of the invention to provide a machine for performing internal grinding operations on a tubular workpiece in which mechanism is provided for feeding the grinding tool into and out of the workpiece at a variable speed whereby greater uniformity and accuracy in the removal of metal from the bore of the workpiece are achieved.

Heretofore, in the use of machines for grinding the bores of tubular workpieces considerable difculties have been encountered owing Vto the inability to grind the bore of the work to a true cylindrical form. It has been found that in the operation of feeding the grinding tool into and out ofthe bore of the Work the tool removed more metal at the ends of the bore than in the middle, resulting in producing a bell mouth or flared condition at opposite ends of the bore, thus preventing the bore from being finished in the grinding operation to a true cylindrical form. This objectionable condition may be due in part to the angular motion of the crank used to reciprocate the grinding spindle resulting in the removal of more metal at the mouths of the workpiece bore than in the intermediate regions. The condition may also be due in part to the time interval involved in bringing the tool to a stop at the end of its traversing movement and reversing its direction of travel. In any event, the operation of prior machines has resulted in producing untrue bores in which the mouth of the bore at each end has been ground to oversize as compared with the remainder of the bore, hence necessitating resort to expensive hand honing operations or manual manipulation of the grinding spindle to true up the bore.

An important object of the present invention,

therefore, is to overcome these disadvantages by modifying the traversing feed of the grinding tool so as to compensate for uneven grinding operation resulting, for example, from the dwell or lag consequent tov starting and stopping the tool or reversing its direction of travel. Hence, in accordance with one aspect of the invention an improved mechanism is provided for imparting a traversing motion to the grinding spindle or tool which will cause the tool to grind or iinish the bore to a substantially truel cylindrical form. In accordance with another aspect of the invention a new and improved method is provided for grinding or finishing the bore of the workpiece so as to overcome the above mentioned disadvantages and produce a iinished bore of substantially uniform dimensions from end to end.

Other objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

Fig. l is a fragmentary perspectiveview of a machine constructed and operable in accordance with the present invention.- I

Fig. 2 is a diagrammatic View illustrating the development of the face of a cam utilizedin controlling the traversing feed` of the grinding spindle.

Fig. 3 is a side view in elevation of the cam.

Fig. 4 is a rear end elevation of the machine.

Fig. 5 is an enlarged sectional elevation taken substantially through lines 5 5 of Fig. 4 looking in the direction of the arrows.

Fig. 6 is a fragmentary plan view taken substantally from lines 6-6 of Fig. 5 looking in the direction of the arrows.

Fig. '7 is an enlarged fragmentary sectional View taken substantially through lines 'l-'I of Fig. 5 looking in the direction of the arrows.

Before explaining in detail the present invention it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrate ed in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also it is to be understood that the phraseolog'y or terminology employed herein is for the purpose of description and not of limitation.

In the drawings there is illustrated, by way of example, a machine for performing internal grinding operations upon a tubular workpiece, such as a bushing W, through the medium of a grinding tool or wheel T. Referring to Figs. 1 and 4, the machine therein illustrated comprises a suitable upright supporting frame I upon which is rigidly mounted a bed or platform II. Rising from the bed at one end of the machine are longitudinally spaced pairs of stanchions I2 and I3 notched at their upper ends to receive a pair of transversely spaced longitudinally extending guide shafts I4 which are rigidly secured to the stanchions. Located above these guide shafts is a horizontal platform or slide I5 having depending transversely spaced bosses I6 bored to receive the guide shafts I4 and through the medium of which the platform I5 is slidable back and forth in a longitudinal direction during the traversing feed of the grinding spindle. The supporting shank for the grinding wheel T is Vreleasably clamped or gripped in conventional manner in a collet carried by a rotary tool carrying or grinding spindle I1 revoluble within a bearing member I8 secured through clamping members I9 and I9a to a slide 20 adjustably bolted to the platform I5 within a transverse way wherein. In accordance with this construction it will be seen that the slide may be shifted transversely of theslide or platform I5 in order to adjust the lateral position of the grinding wheel. The tool carrying spindle I1 is driven through the medium of a belt 2! connected to a driven pulley 22 secured to the spindle and also connected to a driving pulley 23 secured to the driving shaft of an electric motor 24 mounted upon the platform 20.

The improved mechanism for reciprocating the slide I5. and. hence, producing the traversing feed of the grinding spindle and the grinding tool T carried thereby is illustrated particularly in Figs. 5 to 7 inclusive. J ournalled on a transverse pin 25 carried by a depending bracket 26 rigidly secured to the bottom of the slide I5 is one end of a connecting rod 21. The opposite end of the connecting rod is journalled on a transverse pin or stud 28 terminating at its inner end in a square head 28a having a sliding t within a guideway or slot 29 formed in an upwardly extending crank arm 30. The head 28a of the pin 28 may be adjusted into various positions within the guideway 29 longitudinally of the crank 39 and xed in any adjusted position by means of a clamping nut 3| threaded onto the outer end of the pin. As a result of this construction bv which the position of the outer end of the connecting rod 21 is adjusted along the length of the crank 39. the throw of the connecting rod and. hence. the length of traverse of the tool may be varied.

Rigidly secured to the lower end of the crank arm 30 is a transverse shaft32 having a bearing in the wall of a housing 33 open at its upper` end. This housing is mounted upon a lower housing support 34 having an attaching flange 34a abutting against the bottom of the bed II and rigidly bolted thereto. The housings 33 and 34 are secured together by means of bolts 35. The shaft 32 has a splined connection in a cross-head 36 to which the shaft is pinned. Mounted on opposite ends of the cross-head 36 through the medium of ball or other anti-friction bearings are a pair of rollers 31 and 38 which engage the circular cam face 39 of a cam block 4l) disposed within the lower end of the housing member 33. The cam block 4U is supported through the medium of a ball bearing race 4I on the upper face of the housing support 34. Integral with the cam block is a depending shaft 42 of stepped formation which is journalled within vertically spaced ball bearing races 43 and 44.

Keyed to the shaft 42 is a worm gear 45 meshing with a worm 46 keyed to a worm shaft 41 5 mounted in bearings, as illustrated in Fig. '1, in the housing support 34. The shaft 41 projects through an opening in the housing and carries at its outer end a pulley 48 which is fastened to the shaft and which is driven through the medium of a belt 49 from a pulley 50 secured to the armature shaft of an electric motor 5I housed within the frame I9 beneath the bed II, as illustrated in Fig. 4.

In the present machine the workpiece is carried by a rotary work spindle which is supported in such manner that it, may be readily shifted toward and from the tool spindle into and out of operative position with respect thereto, the workpiece being mounted in a chuck or collet carried by the work spindle and the support for the work spindle being pivotally mounted so that by suitable adjustment thereof the workpiece may be shifted laterally with respect to the t-ool during the grinding or machining operation. Mounted in the notched ends of longitudinally spaced pairs of stanchions 52a rising from the bed II are a transversely spaced pair of guide shafts 52 upon which is slidingly mounted a housing support 53 which carries a rotary work spindle 54 in suitable bearings in the upper end thereof. The forward end of this spindle is constructed in any suitable or conventional fashion to receive a collet 55 which in turn receives the tubular workpiece W. The collet is of conventional kind provided with an external tapered portion cooperating with an internal tapered portion on the end of the spindle so that by shifting the collet longitudinally with respect to the spindle the collet may be contracted or expanded to grip or release the workpiece W. The workspindle 54 is driven through the medium of a belt or pulley drive indicated generally at 56 which is operated from the drive shaft of an electric motor 51.

At the commencement of a grinding operation the operator of the machine grasps a handle 58 and shifts the housing support 53 toward the tool spindle to bring the workpiece W into operative position with respect t0 the grinding wheel or tool T. Thereupon the motor 5I is started to reciprocate the grinding wheel into and out of the work to perform the desired grinding operations on the bore of the workpiece. During the grinding operation the work spindle is shifted or adjusted laterally with respect to the tool in order to control the depth of cut of the grinding tool as it is fed through the work. Lateral adjustment of the work spindle is accomplished by swinging the entire housing support 53 about the axis of the guide shaft 52. Since this construction forms 60 no part of the present invention, a further detailed description thereof is deemed unnecessary and reference is had to my copending application Serial No. 537,832, filed May 29, 1944, and which issued as Patent No. 2,401,165, on May 28, 1946, for a description `of the entire work holding mechanism including the details of construction and the mode of operation thereof.

In operation the slide I5 is reciprocated longitudinally by the connecting rod 21 to which reciprocating motion is imparted by the crank 30. The latter is oscillated or swung forwardly and backwardly by the rocking motion imparted to the crosshead 36 through engagement of the rollers 38 with the circular cam face 39 of the rotating cam member 4U. The stroke of the crank 30- and', hence, the stroke of the grinding spindle is determined by the pitch of the inclined cam face 39 which governs the rise and fall of the rollers 31, 38 during rotation of the cam. Variation in the length of the stroke of the grinding spindle may be obtained by adjusting the position` of the. pin 23 within the guideway 29.

Inv order to grind the bore of the workpiece to a true cylindrical form and avoid a bell mouth condition, it is important that the grinding wheel during its reciprocation through the workpiece remove the same amount of metal at all points from one end to the other of the bore. Exact accuracy in the finish operation requires that the longitudinal feed of the grinding Wheel be controlled in such manner that it will make the same number of revolutions at all points in the length of the bore. Heretofore on account of the dwell of the grinding tool occurring at each end of the bore of the workpiece caused by the stopping and starting of the tool and reversingl the direction of feed, more revolutions of the grinding tool were made at the ends of the bore than at points intermediate these ends. These additional revolutions at the ends of the bore resulted in the removal of more metal at these localities and the production of what has been termed a bell mouth condition. This dwell of the tool at the end of the bore has been eliminated in the present, embodiment of the invention by speeding up the linear travel :of the grinding wheel at the outer and inner mouths of the bore, and in the present instance is accomplished by varying the rise and fail of the rollers 31 and 38 on the cam face 39 so that for a predetermined distance of travel at and near each end of the stroke of the tool an accelerated or more rapid rise or fall is imparted to the rollers.

In Figs. 2 and 3 there is illustrated a development of the circular cam face 39 by which the foregoing purposes are accomplished. The low point X on the inclined cam surface is taken as having a Zero elevation and the corresponding point Y on the cam surface opposite the point X and 180 therefrom has an elevation of .875 inch above the point X. The graduations shown on Fig. 2 indicate 10 increments around the circumference of the cam and the figures opposite these graduations indicate the successive heights of the cam surface above the zero elevation at X. The development of the cam in the illustrated example is such that for a distance of 30 from the low point X of the cam in a clockwise direction the progressive rise in pitch is relatively rapid. Thereafter for a distance of 120 the progressive rise in pitch is relatively less and varies to a point 30 in advance of the high point Y of the cam. From this latter point for a distance of 30 the rise in pitch again increases relatively rapidly until the point Y is reached` Thereafter for a distance of 30 beyond the high point Y there is a relatively rapid decline in the pitch. From this latter point for a distance of 120 the decline in pitch of the cam is relatively less and varies to a point 30 in advance of the low point X. From this latter point the decline in pitch is again relatively rapid to the Zero point X,

The position of the cam roller 38 in Fig. 5 is opposite the low point X of the cam surface and the cam roller 31 is positioned opposite the point Y. Thus, as the cam is revolved in the direction of the arrow in Fig. 2 a relatively rapid rise of the cam roller 38 for a distance of 30-occurs and a corresponding fall of the cam roller 31 also occurs for this distance. This produces a more rapid feedof the grinding tool at its entrance into the mouth of the bore and compensates for the lag inl starting or in reversing the direction of feed. Thereafter for a distance of on the cam surface the rise of the cam roller 38 and the corresponding fall of the cam roller 31 are slower, representing the normal feed of the tool within the bore of the work between the opposite open ends of the latter. When the tool reaches the inner end of the workpiece, its rate of linear travel is again increased thus compensating for the dwell due to bringing the tool to a Stop at the end of its travel and reversing its direction of feed. This occurs when the roller 38 approaches the high point Y on the cam which represents the point when the forward feed of the tool is stopped and its direction of feed is reversed. For a distance of 30 at each side of the point Y, therefore, the pitch of the cam surface increases rapidly and thereafter decreases a corresponding degree resulting in speeding up the linear travel of the tool in opposite directions at the inner end of the bore of the workpiece, This same accelerated travel occurs when the grinding tool reaches the open mouth of the bore and its direction of lfeed is again reversed.

In the embodiment illustrated in Figs. 2 and 3 the cam is developed, as above described, for the purpose of offsetting or compensating for the dwell or lag of the tool occurring at each end of the bore of the workpiece, resulting heretofore in more revolutions at these localities and the consequent removal of more stock by the tool. It will be understood that the development of the cam and the differences in pitch may vary from that shown in Fig. 2 in accordance with requirements, the present embodiment being shown for illustrative purposes.' Furthermore, it will be understood that the cam development may also vary from that shown in order to compensate for slight variations in the rate of linear travel of the tool consequent to the angularity of the crank 30. It will be noted from the drawings that the cam `surface across the diameter through points X and Y has its maximum taper transversely. This taper gradually decreases until the cam surface is horizontal across the diameter at right angles v'to the diameter X-Y. This taper at allv points is developed so that the rollers will have full uniform contact with the cam surface during each complete revolution of the cam.

I claim:

1. In a metal working machine having a work holder adapted to support a tubular workpiece, a tool holder having means for supporting a grinding tool, means for reciprocating said tool holder toward and from the work holder including a swinging arm connected adjacent one end to the tool holder, a pair of spaced cam rollers connected to the arm adjacent the opposite end thereof, a circular cam having an inclined cam face engaging said rollers and adapted to impart relative up and down movement to the rollers during rotation of the cam thereby to swing said arm, and means for rotating said cam.

2. In a metal working machine having a work holder adapted to support a tubular workpiece, a tool holder having means for supporting a grinding tool, means for reciprocating said tool holder toward and from the work holder including a swinging arm connected adjacent one end to the tool holder, a pair of spaced cam rollers connected to the arm adjacent the opposite end thereof, a circular cam having an inclined cam face engaging said rollers and adapted to impart relative up and down movement to the rollers during rotation of the cam thereby to swing said arm, and means for rotating said cam, said cam face having a, variable pitch in a circumferential direction.

3. In a metal working machine having a work holder adapted to support a tubular workpiece, a tool holder having means for supporting a grinding tool, means for reciprocating said tool holder toward and from the work holder including a swinging arm connected adjacent one end to the tool holder, a pair of spaced cam rollers connected to the arm adjacent the opposite end thereof, a circular variable pitch cam engaging said rollers and adapted to impart relative but variable up and down movement to the rollers during rotation of the cam thereby to oscillate saidarm, and means for rotating said cam.

4. In a metal working machine having a work holder adapted to support a tubular workpiece, a tool holder having means for supporting a grinding tool, means for reciprocating said tool holder toward and from the work holder including a swinging arm, a pair of cam rollers connected to said arm, a circular cam engaging said rollers and constructed to impart a variable rate of rise and fall to said rollers during rotation of the cam thereby to oscillate said arm at a variable rate of speed, and means for rotating said cam.

5. In a metal working machine having a work holder adapted to support a tubular workpiece, a tool holder having means for supporting a grinding tool, means for reciprocating said tool holder toward and from the work holder including a swinging arm, a pair of cam rollers connected to said arm, a circular cam engaging said rollers and adapted to impart relative up and down movement to the rollers during rotation of the cam to oscillate said arm, said cam having circumferentially spaced portions adapted to impart more rapid up and down movement to the rollers than portions of the cam intermediate said spaced portions, and means for rotating the cam.

6. In a metal working machine having a work holder adapted to support a tubular workpiece, a tool holder having means for supporting a grinding tool, means for reciprocating said tool holder toward and from the work holder including a swinging arm, a pair of cam rollers connected t0 said arm, a circular cam engaging said rollers and adapted to impart relative up and down movement to the rollers during rotation of the cam to oscillate said arm, said cam having portions circumferentially spaced apart adapted to impart more rapid up and down movement to the rollers than portions of the cam intermediate said spaced portions, and means for rotating the cam.

7. In a metal working machine, a tool holder having means for supporting a tool, an arm adapted to oscillate back and forth and connected to said tool holder for oscillating the same, a pair of rollers connected to the arm, a circular cam engaging said rollers and adapted to impart relative motion to the rollers to oscillate said arm during rotation of the cam, and means for rotating said cam, said cam having an inclined roller engaging face of Variable pitch.

8. The method of grinding the bore of a tubular workpiece by means of a grinding wheel, comprising reciprocating said grinding wheel through said bore and imparting a slower rate of linear travel to the grinding wheel while the grinding wheel operates intermediate the ends of the bore than the rate of linear travel of the grinding wheel while operating on one end of the bore.

9. The method of grinding the bore of a tubular workpiece by means of a grinding wheel, comprising reciprocating said grinding wheel through said bore and imparting a slower rate of linear travel to the grinding wheel while the grinding Wheel is operating on an intermediate portion of said bore than on opposite end portions of the bore.

HARRY L. KNAPP.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,231,918 Lewis July 3, 1917 1,933,213 Guild Oct. 31, 1933 2,116,593 Bouvier et al May 10, 1938 2,237,583 Birkigt Apr. 8, 1941 

